As of now, Manhattan Borough President Scott Stringer is likely to become the next comptroller without facing a single opponent in the Democratic primary. And no matter who emerges as his Republican challenger, Stringer will be the prohibitive favorite in the general election.

“It’s unbelievable,” said one political pro. “In a city of 8 million, you’d think someone would turn up.”

But no one has.

It’s hard to recall the last time there was an uncontested race for an open citywide office. Even the lowly job of public advocate, an office with a budget of less than $2 million, has drawn a half-dozen contenders.

Chalk up Stringer’s good fortune to his own hard work, a formidable war chest, fortuitous timing and an awful lot of supporters much happier to see him running for comptroller than for mayor.

“Scott solved a lot of problems for people when he dropped out” of the mayoral race, said one source. “He wasn’t going anywhere, but union guys and electeds felt they had to support him. He was putting a lot of people in a bad spot.”

Once Stringer bumped down to the comptroller’s race in November, those backers heaved a sigh of relief and rushed to his side. Instantly, Team Stringer could boast marquee endorsements from such political stars as Ed Koch, Rep. Jerry Nadler and Gloria Steinem.

Faced with that reality — and Stringer’s $3 million campaign treasury — Manhattan City Councilman Dan Garodnick took 30 seconds to decide that his own quest for comptroller could wait.

The chairman of the council’s Finance Committee was counting on having two Manhattanites in the race to split that borough’s vote. With Garodnick out, so was Recchia.

Taxi chief David Yassky, who ran for comptroller in 2009 and was contemplating taking another shot this year, has his hands full trying to push through the administration’s plan for expanding metered-cab service to the boroughs outside Manhattan. Scratch Yassky.

Stringer still faces one potential threat, in the form of Anthony Weiner, the former congressman, who resigned in a sexting scandal and appears to be contemplating a comeback.

Last month, Weiner paid for a poll to test the waters. Since he still has nearly $4 million in his campaign account, he can’t be written off despite all those troublesome tweets.

But Stringer’s luck is holding. A Marist College poll several days ago showed Weiner with a dismal 34/43 percent positive/negative approval rating among Democrats, a difficult launch pad for a campaign.

Stringer told The Post that he’s campaigning as usual and assuming that his free ride is bound to end.

“I am anticipating a primary or general [election] or both,” he said. “I’m taking nothing for granted.”